Most high production surface coal and iron ore mines utilize a cyclical process that includes drilling holes into the surface, inserting explosives into the holes, igniting the explosives to loosen the material, excavating the loosened material and loading it into haul trucks, transporting the material to a crushing and conveying facility, and depositing sized and sorted materials into appropriate stockpiles. This method has been in used for over 100 years and has been the subject of continuous refinement. The predominant method to excavate and load coal or iron ore is the use of high capacity hydraulic excavators (also referred to as hydraulic mining shovels). The predominant method to remove overburden is to use draglines and/or electric mining shovels. Recently, hydraulic mining shovels have increased in capacity and can now roughly equal the production rates of the smaller electric mining shovels.
Another fairly recent development is the adaptation of road milling machines for surface mining. These adapted road milling machines are typically man riding, diesel powered vehicles with belt driven cutting drums that operate in a fixed relationship to the ground.